Yes you can freeze sliced apples but need to keep them from going brown by squeezing lemon juice on them.

I always make apple sauce with mine - if they're Bramleys, just peel and chop them up, put a tiny drop of water in the bottom of a saucepan (just enough to stop them burning and sticking, but no more) cook for 10 minutes till its all fluffy, cool and freeze. You might want to add sugar to taste, I never do, I just like it as it is with pork! Or even for breakfast, delicious...
If they're just cookers and not bramley, you'll need to mash them up after they're cooked, or whizz them in a processor.

We puree all edible apples, cook gently over a low heat with a little water. then freeze the puree as it is. Done quickly after cooking there is no need for lemon juice, the puree does not go brown. We use the puree in cakes as a sugar substitute and I often have it with some berries of some sort and a little cream as a desert.
You may also turn the windfalls into a very acceptable jam.

How about Blackberry and apple jam or mix the 2 frozen fruits together for a crumble base. Cooking apples form the base of most chutneys and as had been suggested puree and freeze or bottle

Was going to add, like Rozalia, apple chutney with raisons etc is delicious served with cheese.

Thank you for your comments :-) I had thought of making apple & blackberry crumble but I've no idea how long it would need to cook in a gas oven.

How do I prepare apples for cooking in the oven? Do I have to peel, core & slice them?

How do you make apple pie? How do you make the pastry? What sort of recipient would I need to use? This something I've never done before!

Can the apples be used at any time? Gerry says they are very late maturing apples so the ones falling off the tree, even the size of dessert apples, are obviously not ripe yet.

If you can find a suitable small basin that just fits the apple. Wash it, core it and poke raisins or blackberries down the centre and sweeten it as you fill the core. I use sweetener powder and on the skin as well. Cover the basin. Put it in the microwave and give it 2 mins and inspect, then 1or 2 more mins until the skin breaks....... I call this exploded apple. A touch of custard or squirty cream. A quick pud. Lakeland do or did an apple shaped plastic doodah for this very recipe. Found another one in a charity shop recently for 50p.

Balcony you could buy ready made pastry, its very nice and roll it out and voila, you have apple pie !

Shortcrust pastry's easy, specially if you've a processor - 8 oz SR flour, 4 oz fat (butter or Cookeen or Willow or whatever, not Flora or soft spreads) rub the fat into the flour till its like breadcrumbs (or whizz in the processor till its like that) now add water to make a soft but not sticky dough, Roll it out, to the size of the dish you're using (a pie tin or a shallow dish). I'd recommend Cookeen, makes good pastry. There are fancier pastries - some people use an egg yolk to mix as well as a drop of water, or add sugar or salt.
As for baked apples, I don't use any sweetener on mine - core, score horizontally round the skin in the middle of the apple all the way round, stand in a suitable oven dish (I use the bottom of a pyrex casserole that just takes two, or four), drop of water in the bottom, stuff with sultanas, almonds or whatever you've got and half a teaspoon of honey drizzled into the stuffed hole, small knob of butter on top, shove in the oven on about 4 or 5 till cooked.
As for preparation of apples for a pie or tart (pie has a pastry lid as well as a pastry bottom, tart just has a bottom) peel, core and slice, place on pastry - if you're making a tart, you'll need to glaze the tops with something (can't remember what though, someone else might know).
If you want flaky or puff pastry, my recommendation is to buy it ready made - its very good and its such a faff to make yourself. And remember pastry needs a higher temperature than, say, the baked apples - check out the Jusrol packets in the supermarket for temperatures.

Thank you all very much for the answers, especially Bamboo for going to such lengths to give me all the instructions. I shall copy them into a Word Doc & then print them out - just as I did when I was given the crumble mix instructions. :-)

Thank you, too, Dorjac, for the microwave instructions. :-) I'll do the same as for Bamboo's instructions.